Dry markers used on white boards have become increasingly popular in recent years. Such markers are well developed and are currently available in a wide variety of colors, though black is the color most commonly used. Such markers are usually used in conjunction with dry erase boards which have a relatively smooth, non-porous surface so that the marker fluid does not sink into the body of the board to the same degree chalk sinks into a conventional slate blackboard. Such dry boards are also well-known in the art and hence a detailed description of the dry boards is not necessary to an understanding of the invention. Such boards are available in many colors but white is by far the most common color since it provides maximum or near maximum contrast with the marker fluid, particularly black fluid.
Although the marker and board described above are very popular, certain drawbacks have become apparent which pose a nuisance to users.
A significant problem is the fact that it is difficult to remove the markings made by such markers on a dry board if the markings have been on the dry board for a substantial length of time. It will be understood that dry board erasers are available which function very well in removing markings which are fresh from a dry board. Thus, for example, if a teacher uses the above-described marker and board to illustrate a lecture, the board may be covered with markings before the lecture is finished. When this occurs the lecturer simply erases the markings made earlier in the lecture using a conventional dry board eraser and thereby re-creates a clear area on the board, and then begins to re-mark said clear area as the lecture continues. The markings made just moments ago, and other markings made up to a considerably longer period of time such as, for example, during the preceding lecture hour, erase easily with an eraser having a conventional dry board erasing surface. However, when the markings have been on the dry board for an extended period of time, say, for example, over a holiday or during a school closed period of several weeks or several months, the markings which remain from the last use can be removed using a conventional eraser only with great difficulty and with the application of repeated wiping passes under substantial hand-applied pressure. On occasion, even the application of the above-described effort does not result in a clear surface and hence the next user must work with a surface having faint, and possibly not so faint, traces of the markings made by a prior user. The possibility for confusion is obvious.
Prior markings which have been in place on a dry board for a substantial period of time are commonly referred to as stubborn dry erase marks, and that phrase will be used in this description and the accompanying claims to describe such markings.